This invention relates, in general, to the manufacture of semiconductor devices and is directed specifically to an apparatus and method of reducing or eliminating particulate matter, such as dust particles and other debris, within the vacuum chambers of particle beam lithography systems where semiconductor wafers are being transported and processed.
In the process of manufacturing semiconductor devices, such as integrated circuits, semiconductor wafers (also herein called workpieces) for making masks or reticles for integrated circuits are transported, usually on a conveyor, to a loading chamber which is pumped down to a vacuum before the wafers are transported into a vacuum processing chamber in particle beam lithography machine for processing. The conveyor also transports the processed wafers from the processing chamber and loading chamber for further manufacturing processing.
The problem with the transportation of the wafers through the loading chamber and the processing chamber is the accumulation of particulates, such as dust and debris, in certain critical areas in the vacuum chambers generated predominantly by moving parts, such as the rollers of the conveyor, the action of the hinges during the opening and closing of the chamber doors and the like. This dust and debris can become a major source of damage to the wafers and this invention is directed to the solution of this problem by providing a means and method by which such dust and debris are reduced.
Many suggestions have been made for solving this problem but they usually included other active devices which in themselves also generated dust and debris and, in general, complicated the transportation and processing of the wafers in the lithography system.
It is an object of this invention to provide a passive electrostatic particle collector usable in particle beam lithography systems for reducing dust and debris which would otherwise collect on and possibly damage to the wafers during processing.